1. Technical Field of the Invention
The present invention relates to a method of manufacturing a coil assembly unit for a rotary electric machine.
2. Related Art
In general, rotary electric machines, such as motors, generators, and motor generators, need coil assembly units in which coil wires are assembled together to induce current therethrough or generate a magnetic field by supplying current therethrough. To manufacture such coil assembly units, there have been known various manufacturing methods.
For example, Japanese Patent Laid-open Publication No. 2002-176752 discloses one manufacturing method, in which a pair of plate-like winding cores, which are located to be opposed to each other, is used to wind a plurality of coil wires at the same time. Another manufacturing method is disclosed by Japanese Patent Laid-open Publication No. 2004-104841, in which two coils are laced with each other. Practically, in a winding step, the first coil wire is formed into a triangular-waveform coil wire, and in the next step, the second coil wire is turned 90 degrees around the axis thereof during which time the second coil wire is made to advance in the direction along the first coil wire so that an overlapped portion between both coil wires increases by half of one turn. In the next step, the second coil wire is further turned 90 degrees around the axis thereof. Repeating these steps allows the second coil wire to be sequentially woven with the first coil wire by half of the one turn.
As other methods of mutually weaving (i.e., combining, lacing, plaiting, or twining) a plurality of coil wires each having a plurality of turns, the following method can be conceived of. For example, as is performed by known weaving machines, there are known various weaving methods. One method is that another coil wire is rotated around a fixed coil wire, during which time the rotated coil wire is shifted in the longitudinal direction of the fixed coil wire by one coil pitch. Another method is that two coil wires are held to be mutually open from their initial woven portions by a given opening angle, and then mutually woven so that the two coil wires are mutually rotated around the counterpart.
However, to avoid interference between turn portions of the woven coil wires, these methods require that an angle made between the axis lines of the two coil wires be increased. This will thus lead to a problem that the coil wires are likely to deform. Especially, when it is required to manufacture a coil assembly unit for motors having a longer axial length, such deformations may be larger when being woven, because each coil wire has a longer straight portion being accommodated in each slot. If the coil wires are deformed when being woven, the woven coils are also resulted in having distorted shapes, whereby it is difficult to provide coil assembly units with precision.
In addition, the foregoing conceivable weaving methods still have another problem that the coil wires should be rotated at larger angles, resulting in being larger the size of the manufacturing devices. Hence, the manufacturing cost of the devices become higher and it is difficult to manufacture coil assembly units at higher speed.